The development of serologic tests for human babesiosis and granulocytic ehrlichiosis (HGE) is proposed: a dot blot test for screening and immunoblots for confirmation. The dot blot test will simultaneously screen patient serum for antibodies to Babesia microti, HGE and Borrelia burgdorferi, the Lyme disease pathogen. The B. microti and HGE immunoblots will provide a highly sensitive and specific means to confirm the results of the screening test, and may also be used independently to confirm infection based on other clinical or laboratory evidence. These tests will be developed using Immunetics RAFTTM rapid membrane assay technology, providing results in 15 minutes. In Phase I, the screening and immunoblot tests for babesiosis and HGE will be optimized, and prototype commercial kits developed. The tests will be evaluated on a panel of characterized sera including Babesia-and HGE- positive and negative specimens. In Phase II, kits will be extensively evaluated in clinical trials and modified for automation on Immunetics CodaVision immunoassay instrument. These tests will facilitate more accurate and timely diagnosis of babesiosis and HGE, as well as co- infections with Lyme disease, addressing an urgent public health need caused by growing incidence of tick-borne diseases. PROPOSED COMMERCIAL APPLICATION The proposed test for babesiosis and HGE will be the first commercial tests in kit form for these diseases, and will meet a growing demand from reference laboratories, hospital and other clinical laboratories. Development and eventual automation of these tests will eliminate the need for expensive specialty testing and open this market to the average clinical laboratory.